KLF4 N-Terminal Variance Modulates Induced Reprogramming to Pluripotency

Abstract

SummaryAs the quintessential reprogramming model, OCT3/4, SOX2, KLF4, and c-MYC re-wire somatic cells to achieve induced pluripotency. Yet, subtle differences in methodology confound comparative studies of reprogramming mechanisms. Employing transposons, we systematically assessed cellular and molecular hallmarks of mouse somatic cell reprogramming by various polycistronic cassettes. Reprogramming responses varied in the extent of initiation and stabilization of transgene-independent pluripotency. Notably, the cassettes employed one of two KLF4 variants, differing only by nine N-terminal amino acids, which generated dissimilar protein stoichiometry. Extending the shorter variant by nine N-terminal amino acids or augmenting stoichiometry by KLF4 supplementation rescued both protein levels and phenotypic disparities, implicating a threshold in determining reprogramming outcomes. Strikingly, global gene expression patterns elicited by published polycistronic cassettes diverged according to each KLF4 variant. Our data expose a Klf4 reference cDNA variation that alters polycistronic factor stoichiometry, predicts reprogramming hallmarks, and guides comparison of compatible public data sets.

A developmental framework for induced pluripotency

“…Additionally, it has been observed that reprogramming efficiency is enhanced by increasing levels of OCT3/4 and KLF4 (Papapetrou et al, 2009;Tiemann et al, 2011) as well as by lowering SOX2 expression (Yamaguchi et al, 2010). It has also been shown that in the early phase of reprogramming towards pluripotency, OCT3/4 and SOX2 promote the expression of mesendodermal and neuroectodermal genes, respectively (Shu et al, 2013), whereas KLF4 can induce the expression of epidermal genes in a context-dependent manner (Kim et al, 2015). Thus, unbalanced OSKM expression deviates the intermediate cells from the reprogramming path.…”

“…Taken together, these data suggest that both mouse and human intermediate reprogrammed cells go through mesendodermal and epiblast-like states. However, MEF-derived SSEA-1 + intermediates also transiently express several genes associated with the epidermis, a much more specialized tissue derived from the ectoderm, suggesting that reprogramming is not a simple reversal of the normal developmental process (O'Malley et al, 2013;Kim et al, 2015). Such transient expression of developmental genes in intermediate reprogrammed cells is thought to be directly or indirectly regulated by reprogramming factors.…”

Impact of the Monocarboxylate Transporter-1 (MCT1)-Mediated Cellular Import of Lactate on Stemness Properties of Human Pancreatic Adenocarcinoma Cells

“…Meanwhile, several studies have confirmed the fundamental role of the sequential expression of these three reprogramming factors [45][46][47][48]. It can be speculated that the reverse Warburg compartment harbors a subpopulation of cancer cells that are characterized by a quiescent stem cell-like phenotype.…”

KLF4α stimulates breast cancer cell proliferation by acting as a KLF4 antagonist

“…Our data on KLF4α in breast cancer mostly confirms this study with some significant novel additions and relevant differences: (i) Compared to Wei et al [26] our sequencing analysis showed that MDA-MB-231 cells contain a KLF4 protein with nine additional N-terminal amino acids (MRQPPGESD) corresponding to the EMBL Nucleotide Sequence Database accession number HF546201. This N-terminal variance in KLF4 has recently been identified and characterized for the potential of reprogramming [39]. (ii) KLF4α expression has been described in pancreatic and prostatic cancer only [25, 26].…”